Quantum Magnetic proposes to develop an instrument, configured as a magnetic gradiometer, that would locate and track a magnetic target in the human digestive tract without the use of radioactive markers. The focus application is to track capsules that are used to study the effects of new medication; however this method may be extended to other applications such as the measurement of gastric motility. Once the target is placed in the capsule, magnetized, and swallowed, its progress will be tracked by the instrument by measuring its magnetic field. When the capsule dissolves, the target will disintegrate, thereby losing its magnetization. The remnants of the magnetic target may then be tracked by measuring their response to an applied magnetic field. The magnetic tracking method will overcome many of the disadvantages of the radioscintigraphic method and make it possible to (a) do measurements in pregnant women and children, (b) avoid patient exposure, however little, to radiation, (c) allow gastroenterologists to use a significantly less expensive instrument, and (d) significantly ease target preparation. In Phase I we will demonstrate the feasibility of the proposed technique and specify the design of a prototype instrument to be built and tested in Phase II. PROPOSED COMMERCIAL APPLICATION: The proposed research will lead to an instrument that will enable gastroenterologists to track objects within the digestive system without using radioactive markers. This instrument will offer significant cost savings and independence to gastroenterologists, and will allow measurements in pregnant women and children to study the effects of new medication. The instrument will be of interest to gastroenterology departments and many pharmaceutical manufacturers worldwide.